It would appear as though many of the functions of a "transport firewall" would serve the purposes of a service oriented architecture, however an additional layer will likely be necessary. Let's assume that a transport firewall has two primary levels of protection:
1. Packet Filerting (TCP/UDP) Level (IP Source, Port, etc.)
2. Protocol Intrinsic Command Level (FTP-PUT, HTTP-GET)
First, we can assume that most firewalls will be able to identify SOAP messages (Protocol Intrinsic Commands), thus allowing those messages to pass through.
In addition, filtering based on SOAP contents will be needed. The SOAP firewall will be required to look at the ws-routing information and determine if the SOAP routing information is acceptable (valid source, valid destination, valid intermediary). The firewall may (or may not) use additional information (beyond IP address) to identify a valid trading partner. In this setting, the SOAP firewall is acting as a first line of defense (bastion).
Note: The SOAP Router will act as the bastion when the message contains bogus routing information.
Note: A level 4 SOAP firewall may determine if the service / operation is acceptable for the given trading partner.
Note: Scoped out of the SOAP firewall are individual service security devices; these will be placed close to the service (hash, authenticate, access control). In this setting, we end up with distributed security - macro at the firewall, micro at the service.